Problem with 12 volt side of electrical

[Tim-n-Deb]

We are currently at a park in Arizona and started having 12 volt electrical problems. All is fine until we turn on a light (bedroom, kitchen, or even open fridge door). The light will come on for a split second and turn off. The Intellitec EMS panel will either dim really low or turn off. When the panel comes back on, it will have random flashing lights. All power (120 and 12 volt) will turn off and come back on. This only happens when using 12 volt items. 120 volt items are fine (a/c, TV's, 120v lighting). We are hooked up to 30 amp service and it is fine.

Everything is working OK except the 12 volts. No breakers trip, no fuses blown. House and coach batteries are charged.

We have the following:
2008 Fleetwood Expedition diesel
4- 6 volt golf cart batteries for the house
Intellitec Smart EMS model 900
Magnum Energy Inverter/Charger model MS2000
Progressive Industries EMS model HW50C
Battery Control Center by RV Custom Products
Kill-A-Watt (it says all electrical is fine)

Battery charger is on float at 13.2

I have looked around to find a converter but can't find one. Not sure if I have a stand-alone one.

Any ideas on where to start troubleshooting?

[Tim-n-Deb]

After I wrote this post, I went about checking all that I could. 1st thing checked: Batteries and cables. The terminals were dirty so started taking each one apart to clean and reassemble. About the fifth terminal in, the cable just fell off from the battery post. The cable lug was eaten through so it was just touching the ring part on the battery post. Finished cleaning the rest, replaced the terminal lug and reassembled. Turned on all power and now ALL is working as should! I guess it does pay to check the easy and obvious stuff first. Thanks for your help.

[time2roll]

Sounds like a poor connection from the battery to the main 12v fuse-distribution consol. Verify battery voltage. Then monitor voltage at the 12v fuses as you turn on a light.

Could be anything from a lose connection at the battery, fuse, switch or ground.

[westend]

You have a converter. It is in the distribution panel space. How are you measuring the float charge of the batteries?

It sounds to me like you have a fault in the 12 V system causing the auto resetting circuit breaker to trip and also causing one of the EMS devices to hiccup. I would be centering diagnosis around the converter and associated 12 V wiring.

[MrWizard]

start here

Magnum Energy Inverter/Charger model MS2000

you don't have a separate converter

unplug from shore power turn inverter off
check battery

your battery is dead, and the charge section of your magnum is not supplying enough power for the lights etc, the 12v shuts off when you try to turn something on, a total reset might fix the magnum, but if it don't then you will need to replace it,
disconnect and test the battery, do you have a backup stand alone battery charger you can charge the battery with